11:00 〜 13:00
[SSS11-P04] A study on detection of low-frequency earthquakes at Mt. Fuji and data quality evaluation
キーワード：火山、地震、低周波地震、富士山、規模別頻度分布、ETAS
Results of detecting low-frequency earthquakes (LFs) occurring at Mt. Fuji, Japan, using the matched filter method (MF method: e.g., Peng & Zhao, 2009) are presented. A system using the MF method for detecting LFs at Hakone volcano, Japan (Yukutake, 2017; Yukutake et al., 2019), was modified to be applicable to the detection of LFs at Mt. Fuji. This system was applied to continuous waveform records at 16 seismic stations around Mt. Fuji during the period of 2000-2019. We prepared template waveforms of 27 LFs on the basis of the earthquake catalog maintained by the Japan Meteorological Agency (JMA). Cross-correlation analysis between the template waveforms and the continuous waveform records was conducted.
A catalog of LFs was created: 3,456 LFs occurred in 2000-2019, which is about 1.4 times higher than the number of 2,464 LFs listed in the JMA catalog in the same period. False detection of LFs seems to be observed. Temporal behavior of LFs in the catalog created in this study, after removing falsely detected LFs from the created catalog, is similar to that in the JMA catalog.
Quality evaluation analysis was conducted in terms of catalog completeness, the Gutenberg-Richter (GR) frequency-magnitude distribution (Gutenberg and Richter, 1944), and the ETAS (Epidemic-type aftershock sequence) model (Ogata, 1985, 1988, 1989). Small LFs are likely to be missing from the LF catalog. Larger LFs tend to have fewer numbers and smaller LFs tend to have more numbers. The b-value of the GR law is applicable to LFs, a feature found by using the JMA catalog. Applicability of ETAS to the LF catalog created using the MF method is similar to that to the JMA catalog.
We are in process to re-create a catalog of LFs, using the increased number of template LFs. Our presentation will include the most recent results.
The authors thank Y. Noda and T. Kumazawa for discussion. This study was partially supported by JSPS KAKENHI Grant Numbers JP20K05050, JP21K04613, the Chubu Electric Power’s research based on selected proposals, the Consortium of Universities & Local Communities in Shizuoka, and the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, under STAR-E (Seismology TowArd Research innovation with data of Earthquake) Program Grant Number JPJ010217. We used JMA earthquake catalog and the waveform records obtained from the permanent stations of National Research Institute for Earth Science and Disaster Resilience, Earthquake Research Institute University of Tokyo, JMA, and Hot Springs Research Institute of Kanagawa Prefectural Government.
A catalog of LFs was created: 3,456 LFs occurred in 2000-2019, which is about 1.4 times higher than the number of 2,464 LFs listed in the JMA catalog in the same period. False detection of LFs seems to be observed. Temporal behavior of LFs in the catalog created in this study, after removing falsely detected LFs from the created catalog, is similar to that in the JMA catalog.
Quality evaluation analysis was conducted in terms of catalog completeness, the Gutenberg-Richter (GR) frequency-magnitude distribution (Gutenberg and Richter, 1944), and the ETAS (Epidemic-type aftershock sequence) model (Ogata, 1985, 1988, 1989). Small LFs are likely to be missing from the LF catalog. Larger LFs tend to have fewer numbers and smaller LFs tend to have more numbers. The b-value of the GR law is applicable to LFs, a feature found by using the JMA catalog. Applicability of ETAS to the LF catalog created using the MF method is similar to that to the JMA catalog.
We are in process to re-create a catalog of LFs, using the increased number of template LFs. Our presentation will include the most recent results.
The authors thank Y. Noda and T. Kumazawa for discussion. This study was partially supported by JSPS KAKENHI Grant Numbers JP20K05050, JP21K04613, the Chubu Electric Power’s research based on selected proposals, the Consortium of Universities & Local Communities in Shizuoka, and the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, under STAR-E (Seismology TowArd Research innovation with data of Earthquake) Program Grant Number JPJ010217. We used JMA earthquake catalog and the waveform records obtained from the permanent stations of National Research Institute for Earth Science and Disaster Resilience, Earthquake Research Institute University of Tokyo, JMA, and Hot Springs Research Institute of Kanagawa Prefectural Government.